1. Field of the Invention
The present invention relates to the field of simulated filters, particularly those which include S-plane zeros.
2. Prior Art
It is well-known to simulate RLC ladder networks with active circuit devices by interconnecting a plurality of integrators. The integrators are most often operational amplifiers employing feedback to provide the integration function. In practice, these filters cannot easily be realized as integrated circuits, but rather are generally hybrid circuits since precision components are needed in the feedback path.
The present invention provides unique coupling between the integrators in an LC simulated filter which results in transmission zeros in the filter's characteristics. This coupling consists of resistive coupling in the presently preferred embodiment, and thus the transmission zeros are obtained without additional active circuit components. Moreover, the disclosed circuit is realizable as an integrated circuit.
The prior art and the improvement of the present invention are described in greater detail in conjunction with the FIGURES.